The entire disclosure of Japanese Patent Application No. 2002-258845 filed on Sep. 4, 2002 including the specification, claims, drawings and summary is incorporated herein by reference in its entirety.
The present invention relates to an electrical conductor assembly contained in an electrical connection box, such as a junction box mounted on an automobile, and more particularly to an electrical conductor assembly where a bus bar and an intermediate terminal to be connected to the bus bar are made of recyclable material.
Bus bars produced by punching an electrical conductive metal plate are contained in electrical connection boxes such as a junction box to form an internal circuit. A tab is formed by bending an end of the bus bar. The tab is connected, through an intermediate terminal, to a relay terminal, a fuse, or a connector mounted in the electrical connection box.
For convenience of explanation, a conventional electrical conductor assembly will be described by referring to FIGS. 5 to 7. FIG. 5 is an exploded perspective view of a conventional electrical connection box for an automobile. FIG. 6 is a perspective view of a conventional intermediate terminal. FIG. 7 is an explanatory view illustrating a problem caused in the conventional intermediate terminal.
More particularly, as shown in FIG. 5, an electrical connection box 1 includes a casing with an upper casing member 2 and a lower casing member 5. Bus bars 4 and insulation plates 3 are laminated alternately on each other in the casing. An end of each bus bar 4 is bent to form a tab 4a. The tabs 4a of the bus bar 4 are connected to intermediate terminals 6.
The tabs 4a penetrate a connector containing section 2a in the upper casing member 2 (and/or lower casing member 5), a fuse containing section 2b, and a relay containing section 2c. The tabs 4a of the bus bars 4 are connected to terminals T of a connector C coupled to a wire harness W/H, a fuse F, and a relay R through the intermediate terminals 6.
Heretofore, the bus bars 4 and intermediate terminals 6, which constitutes the internal circuits, were formed by punching and then bending a copper-based metal plate having a high electrical conductivity. For example, as shown in FIG. 6, the punched copper-based metal plate is bent into tube-like bodies to define slits between the opposed side ends. Thus, each intermediate terminal 6 has upper and lower arcuate contact portions 6a and 6b. The tab 4a of the bus bar 4 is pushed into the lower contact portion 6b through a lower opening in the intermediate terminal 6. The terminal T of the relay R or the like is pushed into the upper contact portion 6a through an upper opening in the intermediate terminal 6. Consequently, the relay R is electrically coupled through the intermediate terminal 6 to the bus bar 1. Alternatively, a pair of tabs of the bus bar, connected to the respective terminals T, may be pushed into the upper and lower contact portions 6a and 6b of the intermediate terminal 6.
Recently, requirement necessitate enhanced recyclability of junked automobiles. Iron makes up the largest part of an automobile. When the junked automobile is thrown into an incinerator to recover and recycle iron, it is required that a mixing rate of copper to iron should be less than 0.1%. This prevents the iron from being denatured due to a reaction with copper.
Since the bus bars 4 are made of a copper-based metal plate, as described above, it is preferable to remove the bus bars 4 from the car body upon disassembly of the automobile and to separate the bus bars 4 from the car body made of an iron-based metal. However, the electrical connection box must be disassembled in order to remove the bus bars 4 from the electrical connection box 1. This work requires intense manpower and is not a practical matter.
To avoid interference with the recovery of iron as a practical matter from a recycling standpoint, it is desirable to select the bus bar 4 from an aluminum-based metal that will not denatured the reaction with the iron. In addition, the aluminum-based metal has an advantage of providing good workability as well as being lightweight.
However, there is a problem in the following case. In the case where the bus bar 4 is made of an aluminum-based metal plate and the intermediate terminal 6 is made of a copper-based metal plate, electric erosion is caused between the different kinds of metals. Accordingly, if the bus bar 4 is made of the aluminum-based metal plate, it is preferable to make the intermediate terminal 6 from the aluminum-based metal plate. However, in this case where the intermediate terminal is made of the aluminum-based metal, since the aluminum-based metal has no elastic function, a desired contact pressure cannot be obtained between the intermediate terminal and the tab. Thus, reliability of the electrical connection is lowered.
The conventional intermediate terminal 6 shown in FIG. 6 is made of the copper-based metal plate having an elastic function. The arcuate contact portions 6a and 6b exhibit the elastic function and can exert a desired contact pressure between the intermediate terminal and the tab. In FIG. 7, a similar intermediate terminal 6xe2x80x2 is made of the aluminum-based metal plate. Contact portions 6axe2x80x2 and 6bxe2x80x2 remain in their deformed positions and do not return to their original positions when the tab of the bus bar or the relay terminal T or the like is pushed into the contact portions 6axe2x80x2 and 6bxe2x80x2. This is due to the aluminum-based metal plates lack of an elastic function. Thus, the desired contact pressure cannot be obtained.
In view of the above problems, it is an object of the present invention to provide an electrical conductor assembly where a bus bar and an intermediate terminal are made of an aluminum-based metal plate. This enhances the recyclability of the automobile and obtains the desired contact pressure between the intermediate terminal and the tab formed on the bus bar. Thus, enhanced reliability of the electrical connection is achieved.
Still other objects and advantages of the invention will become apparent after viewing of the present specification.
In order to overcome the above problems, the present invention provides an electrical conductor assembly contained in an electrical connection box to be mounted on an automobile. The electrical conductor assembly comprises a bus bar produced by punching an aluminum-based metal plate into a desired circuit configuration. The bus bar is provided on an end with a tab formed by bending the end. An intermediate terminal is adapted to be coupled to the tab. The intermediate terminal includes a rectangular parallelepiped box having openings in the opposite ends. The intermediate terminal is made of an iron-based metal plate having an elastic function. A pair of terminal plates oppose each other in the box. Each of the pair of terminal plates is provided on upper and lower positions with arcuately bent contact portions. The rectangular parallelepiped box is provided on each of opposed peripheral walls. A spring portion is in the parallelepiped box. The spring portion comes into contact with a rear surface of each contact portion. The tab of the bus bar is inserted into an end opening in the intermediate terminal. Thus, the tab is forcedly inserted between the contact portions on one side of the terminal plates.
It is preferable that the above box has a high elastic function and stiffness. The box is produced by bending a stainless steel plate. The box does not cause electric erosions even if the box comes into contact with a terminal plate made of an aluminum-based metal plate.
In order to incorporate the pair of terminal plates into the box, each of the pair of terminal plates is provided on each of upper and lower ends with a hook-like latch portion. The hook-like latch portion is hooked on each of upper and lower end edges of the box to attach the terminal plate to the box.
The present invention is not limited to the above coupling construction between the box and the terminal plates. The present invention can utilize various kinds of coupling such as a convexo-concave fitting.
According to the construction of the electrical conductor assembly, in the electrical connection box to be mounted on an automobile, the bus bar is made of an aluminum-based metal instead of a copper-based metal. The mixing rate of copper to iron can be reduced which has caused problems with the recovery of iron during recycling of car bodies in the prior art. Also, since the terminal plates of the intermediate terminal, which contact the aluminum-based press contact tab of the bus bar, are made of aluminum-based metal plate it is possible to prevent the press contact portions from suffering from electric erosions.
The intermediate terminal is made of the aluminum-based metal plate having no elastic function. However, the spring pieces of the box, made from stainless steel having an elastic function, push the press contact portions of the terminal plates to give the elastic function to the terminal plates. Accordingly, it is possible to bring the tab of the bus bar into contact with the terminal plates of the intermediate terminal with a desired contact pressure.